Usually, wheat flour and its mixture with rye flour are used as a major material in bakery products. Only wheat flour gives bakery products having a satisfactory bulge when used alone. It is known that “gluten”, a gummy substance with a high viscosity and elasticity, is formed with gliadin and glutenin, both proteins presented in wheat, by adding water to wheat flour and kneading the resultant mixture. Gluten is known to have a function of embracing carbon dioxide, which is formed in dough by fermentation, and to increase the bulk of bakery products. Therefore, at present, wheat flours suitable for producing bakery products are selected by taking account of breed and producing-country of wheat because the applicability of wheat flours highly depends on the quantity and quality of proteins contained therein.
Most of the wheat used in Japan has been imported from abroad, while rice can be covered with domestic products and is the staple food for Japanese from a long time ago. Therefore, it would be meaningful to use rice for producing bakery products: There have been proposed methods which rice flour is used instead of wheat flour for producing bakery products. For example, processes for producing bakery products with the purpose of substituting some or large part of wheat flour with rice flour, are disclosed in Japanese Patent Kokai Nos. 15,298/93 and 225,661/99. In addition, processes for producing bakery products using rice flour alone are disclosed in Japanese Patent Kokai Nos. 7,071/94, 32,706/99, and 327,242/2001.
However, rice flours have different properties with those of wheat flours. Rice flour to be used for producing bakery products has been produced, usually, by using rice treated in such a manner prior to use as a material, and the resultant rice flour exhibits similar properties with wheat flour. There are several processes for treating rice: For example, a process comprising the steps of soaking rice in a solution comprising pectinase, dehydrating the soaked rice, milling the rice into a fine rice flour, drying the flour to give a moisture content of about 15%, and baking the resulting flour at about 150° C. as disclosed in Japanese Patent Kokai No. 287,652/92; a process comprising the steps of soaking a material rice in a solution comprising enzymes such as hemicellulase, pectinase, and pectin esterase, drying the rice, and milling the dried rice as disclosed in Japanese Patent Kokai No. 68,468/93; and a process comprising the steps of soaking rice in a solution comprising salts of organic acids or salts of organic acids and pectinase, dehydrating and drying the rice, and milling the resulting rice as disclosed in Japanese Patent Kokai No. 175,636/2000, have been proposed. Further, a process for producing bakery products using pre-fermented sponge prepared by admixing “ionized calcium” (monomolecular calcium) with rice flour comprising gluten has been disclosed in Japanese Patent Kokai No. 327,242/2001. However, the effect of “ionized calcium” has not yet been revealed in detail.
As disclosed in Japanese Patent Kokai Nos. 225,661/99 and 32,706/99, in the production of bakery products, it is generally known that a dough with a high rice flour content shows a relatively high adherability and unsatisfactory handleability and mechanical aptitude. It is also known that doughs and bakery products, prepared by using a powder comprising rice flour and gluten, show unsatisfactory characteristics of:                The above doughs are non-uniform and easily separated because of the poor binding of rice flour and gluten;        The preparation of dough is difficult; and        The above bakery products have a small bulk and unsatisfactory mouthfeel.        
When tried to prepare bakery products using a material prepared by adding small amount of gluten to rice flour, the present inventors also found that the fermentation time of dough for fermentation step became short and this resulted in a reduction of working efficiency for producing bakery products in practical production. Also, the bakery products showed an unsatisfactory grain, small increase of bulks, and tough mouthfeel. Furthermore, the bakery products stiffened and did not rise because of insufficient evaporation of moisture during the baking and had no crust and poor appearance by white-tinged crust color. In addition, the resulting bakery products had several disadvantages of staling rapidly during preservation and stiffening easily.
The first object of the present invention is to provide a process for producing bakery products which have improved qualities in appearance, crumb, taste, preservability, etc., and have a satisfactory working efficiency for producing bakery products using dough prepared from rice flour as a major material as in the case of using dough prepared from wheat flour as a major material. The second object of the present invention is to provide bakery products, having satisfactory qualities, produced by the process. The third object of the present invention is to provide premixed flours for producing the bakery products. The fourth object of the present invention is to provide fermented doughs for producing the bakery products.